Set in the early 1900s, Bunuel's surprisingly mainstream and riveting romantic melodrama is the powerful tale of two escaped convicts, Gerardo (Jorge Negrete) and Demetrio (Julio Villarreal), who convince and Argentinean oil magnate to let them work on his rig. When he suddenly disappears, his sister (Libertad Lamarque) immediately suspects the two workers of foul play, but her attraction to Gerardo soon leads her to secretly team up with him to conduct their own murder investigation.